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Jean Piaget's Stages of Cognitive Development

Jean Piaget’s prominent work is his theory on the four stages of cognitive development.Cognitive development is our mental activities such as thinking, perceiving, remembering, believing, and reasoning (Singer & Revenson, 1997, p. 12). He was one of the most influential researchers in the area of developmental psychology in the 20th century whose primary interest was in biological influences on how we come to know, and the developmental stages we move through as we acquire this ability (Singer & Revenson, 1997, p. 13).

Piaget (1973) believed that the child plays an active role in the growth of intelligence and learns by doing. He regarded the child as a philosopher who perceives the world only as he has experienced it. Therefore, most of Piaget’s inspiration in cognitive and intellectual development Development is a biological term referring to physical growth over time. In psychology, development involves the growth of an individual’s thinking, emotions, and strategies for coping with the environment (Singer & Revenson, 1997, p. 12). came from observations of children. In fact, Piaget observed and studied his own three children through each stage of their cognitive development.

The theory of cognitive development focuses on mental processes such as perceiving, remembering, believing, and reasoning. Reasoning is the essence of intelligence, and reasoning is what Piaget studied in order to discover “how we come to know” (Singer & Revenson, 1997, p. 13). Piaget believed that cognitive development is cumulative; that is, understanding a new experience grows out of a previous learning experience.

Description of Piaget’s Theory on the Stages of Cognitive Development

Piaget (1973) developed a systematic study of cognitive development in children. His work included a theory on cognitive development, detailed observational studies of cognition in children, and a series of tests to reveal differing cognitive abilities.

Through his work, Piaget (1973) showed that children think in considerably different ways than adults do. This did not mean that children thought at a less intelligent degree, or at a slower pace, they just thought differently when compared to adults. Piaget’s work showed that children are born with a very basic genetically inherited mental structure that evolves and is the foundation for all subsequent learning and knowledge. He saw cognitive development as a progressive reorganization of mental processes resulting from maturation and experience.

Piaget (1973) believed children will construct an understanding of the world around them, and will then experience discrepancies between what they already know and what they discover in their environment.

To explain his theory, Piaget used the concept of stages to describe development as a sequence of the four following stages:

  1. Sensory-Motor Stage
  2. Preoperational stage
  3. Stage of Concrete Operations
  4. Stage of Formal Operations

Singer and Revenson (1997) explain that these stages unfold over time, and all children will pass through them all in order to achieve an adult level of intellectual functioning. The later stages evolve from and are built on earlier ones. They point out that the sequence of stages is fixed and unchangeable and children cannot skip a stage. They all proceed through the stages in the same order, even though they may progress through them at different rates (p. 18).

At each stage, the child will acquire more complex motor skills and cognitive abilities. Although different behaviours characterize different stages, the transition between stages is gradual, and a child moves between stages so subtly that he may not be aware of new perspectives gained. However, at each stage there are definite accompanying developmental changes in the areas of play, language, morality, space, time, and number (Singer & Revenson, 1997).

Main Elements of Piaget’s Cognitive Development Theory

There are three elements to Piaget’s theory:

  1. Schema
  2. The four processes that enable the transition from one stage to another
  3. The four stages of cognitive development


A schema is the basic building block of intelligent behaviour, a form of organizing information that a person uses to interpret the things he or she sees, hears, smell, and touches (Singer & Revenson, 1997). A schema can be thought of as a unit of knowledge, relating to one aspect of the world including objects, actions, and abstract (theoretical) concepts. We use schemas to understand and to respond to situations. We store them and apply them when needed.

A child is considered to be in a state of equilibrium or in a state of cognitive balance when she or he is capable of explaining what he or she is perceiving (schema) at the time.

The dual processes of assimilation and accommodation (described below) are the building blocks to forming a schema.

The Four Processes:

The four processes that enable the transition from one cognitive stage to another are assimilation,Assimilation is the process of taking in new information and fitting it into a preconceived notion about objects or the world. accommodation,Accommodation is the process of adjusting to new experiences or objects by revising the old plan to fit new information. disequilibrium,Disequilibrium is a state of confusion, dissonance, or discomfort when new information does not integrate within existing structures. This confusion motivates us to achieve the new challenge and to restore balance between assimilation and accommodation, which when achieved, is equilibration. and equilibration. Equilibration is the balance between the processes of assimilation and accommodation. It is the force that drives the learning process to restore balance by mastering the new challenge (information) presented.Educators generally view these processes as an explanation of cognitive learning processes, not just those that lead to major shifts in cognitive ability (Piaget, 1973, p. 36).

Together, assimilation and accommodation are processes of adjustment to changes in the environment and are defined as adaptation, the continuous process of using the environment to learn. And, according to Piaget, adaptation is the most important principle of human functioning.

The Four Stages of Cognitive Development:

Piaget identified the following four stages in development of cognition:

Piaget (1973) describes the four stages as follows:

Sensory-Motor Stage: Ages Birth through Two

The following information of the sensory-motor stage is a summary from Piaget (1973, p. 36).

The Sensory-Motor Stage extends from birth until approximately the age of two. During this stage senses, reflexes, and motor abilities develop rapidly. Intelligence is first displayed when reflex movements become more refined, such as when an infant will reach for a preferred toy, and will suck on a nipple and not a pacifier when hungry. Understanding of the world involves only perceptions and objects with which the infant has directly experienced. Actions discovered first by accident are repeated and applied to new situations to obtain the same results.

Toward the end of the sensory-motor stage, the ability to form primitive mental images develops as the infant acquires object permanence. Until then, an infant doesn’t realize that objects can exist apart from him or herself.

Preoperational Stage: Ages Two through Seven

The following information of the preoperational stage is a summary from Piaget (1973, p. 36).

The child in the preoperational stage is not yet able to think logically. With the acquisition of language, the child is able to represent the world through mental images and symbols, but in this stage, these symbols depend on his own perception and his intuition. The preoperational child is completely egocentric. Although he is beginning to take greater interest in objects and people around him, he sees them from only one point of view: his own. This stage may be the age of curiosity; preschoolers are always questioning and investigating new things. Since they know the world only from their limited experience, they make up explanations when they don’t have one.

It is during the preoperational stage that children’s’ thought differs the most from adult thoughts.

Stage of Concrete Operations: Ages Seven through Eleven

The following information of the stage of concrete operations is a summary from Piaget (1973, p. 36).

The stage of concrete operations begins when the child is able to perform mental operations. Piaget defines a mental operation as an interiorized action, an action performed in the mind. Mental operations permit the child to think about physical actions that he or she previously performed. The preoperational child could count from one to ten, but the actual understanding that one stands for one object only appears in the stage of concrete operations.

The primary characteristic of concrete operational thought is its reversibility. The child can mentally reverse the direction of his or her thought. A child knows that something that he can add, he can also subtract. He or she can trace her route to school and then follow it back home, or picture where she has left a toy without a haphazard exploration of the entire house. A child at this stage is able to do simple mathematical operations. Operations are labeled “concrete” because they apply only to those objects that are physically present.

Conservation is the major acquisition of the concrete operational stage. Piaget defines conservation as the ability to see that objects or quantities remain the same despite a change in their physical appearance. Children learn to conserve such quantities as number, substance (mass), area, weight, and volume; though they may not achieve all concepts at the same time.

Stage of Formal Operations: Ages Eleven through Sixteen

The following information of the stage of formal operations is a summary from Piaget (1973, p. 36).

The child in the concrete operational stage deals with the present, the here and now; the child who can use formal operational thought can think about the future, the abstract, the hypothetical.

Piaget’s final stage coincides with the beginning of adolescence, and marks the start of abstract thought and deductive reasoning. Thought is more flexible, rational, and systematic. The individual can now conceive all the possible ways they can solve a problem, and can approach a problem from several points of view.

The adolescent can think about thoughts and “operate on operations, not just concrete objects. He or she can think about such abstract concepts as space and time. The adolescent develops an inner value system and a sense of moral judgment. He or she now has the necessary “mental tools” for living his life.


Singer, D.G. & Revenson, T.A. (1997). A Piaget Primer: How a Child Thinks (Revised Edition). Madison, Connecticut: International Universities Press Inc.

Piaget, J. (1973). Main Trends in Psychology. London: George Allen & Unwin.